This study explored the effectiveness of mobile learning in foreign language education. With this purpose, instructional materials to be delivered through mobile phones operated in second generation GSM technology in order to improve English language learners' vocabulary acquisition were developed. The multimedia messages in this study allowed students to see the definitions of words, example sentences, related visual representations, and pronunciations. After students finished reading multimedia messages, interactive short message service (SMS) quizzes for testing their learning were sent. In addition, the study examined students' tendencies in using MMS in their second language vocabulary study and explored the opinions of the students toward the use of mobile phones for instructional purposes. The findings of this study suggest some important points to consider while creating MMS content and a SMS quiz system for educational purposes.